Recently, dipeptides have been a target for intensive studies for their physiological functions in mammals. Most of the studies focus on the antioxidant properties of the dipeptides (Boldyrev AA et. al., Mol Chem Neuropathol 1993 May-June, 19(1-2): 185-92; Huang S C and Kuo J C, Proc Natl Sci Counc Repub China B. 2000 October, 24(4): 193-201; Candlish J K and Das N P, 1996 September, 9(2-3): 117-23; and MacFarlane N et. al., J Mol Cell Cardiol. 1991 November, 23(11): 1205-7), which directly or indirectly relate. to anti-cancer activities (Nagai K and Suda T, 1988 August, 10(8): 497-507; and Holliday R and McFarland G A, Br J Cancer 1996 April, 73(8):966-71), immunity enhancement (Boldyrev A A and Severin S E, Adv Enzyme Regul, 1990, 30:175-94), fat reduction (Chan WK et. al., 1994- July, 29(7):461-6), wound healing improvement (Nagai K and Suda T, 1988 August;10(8):497-507), etc. Carnosine is a dipeptide composed of histidine and alanine. Anserine is a dipeptide found in muscle and formed by a peptide bond between alanine and methyl-histidine. Carnosine and anserine, two highly related compounds, have been indicated for the activities and properties described above by many researchers. In addition, carnosine and anserine have also been shown to have the activities of increasing the speed of cell mitosis through stimulation of neutrophils, thus potentially strengthening the repairing. mechanism of muscle tissues under stress (Tan K M and Candlish J K, 1998 August, 20(4): 239-44).
With these functions in mind, recent studies in fatigue relieve have led to the development and commercialization of a highly concentrated anserine derived from marine sources that could reduce the content of muscular lactic acid and the level of carnitine phosphokinase, and effectively increase the stress-endurance level of muscle (Kazuo Sakai et. al., 2000, “Development of Industrial Refning and Separation Technology for Dipeptides, Anserine and Carnosine, from Fish Boiling Juice and Their Functional Property.” Yaizu Suisan Chemical Co., Ltd.). Anserine and carnosine, being highly stable dipeptides, remain intact under low pH (<3.0), and resist against digestion by peptidase and proteases excreted from pancreas or other digestive organs. The dipeptides would find their way through the intestinal membranes, enter blood stream intact, and exert their function directly upon target organs such as liver, kidney and heart. Other dipeptides, such as carcinine, homocarnosine and ophidine, having similar structures to anserine and carnosine are naturally occurring or can be artificially synthesized.
A high level of uric acid may induce gout with symptoms such as muscle spasm, localized swelling, inflammation, joint pains, muscle fatigue, stress feelings and myocardial infraction. Many commercialized drugs have been used to treat gout, such as Benzbromarone (URINORM), Probenecid, Allopurinol, Bucolome, Cinchophan and Colchicine. These drugs work by inhibiting the formation of uric acid, removing the extra uric acid from the body, acting on the kidneys to help the body to eliminate uric acid, inhibiting the activity of xanthine oxidase for the conversion xanthine to uric acid, and accelerating the excretion of uric acid from the body. However, these uricosuric agents simultaneously exhibit a number of side effects such as urinary calculus, gastrointestinal obstruction, jaundice and anemia. Therefore, while there are numerous agents for treating gout, there is still a need for a new drug or a dietary supplement for reducing the level of uric acid and thereby treating gout and moderating gout-related symptoms.